Lockheed Martin F-22 Raptor
The Lockheed Martin F-22 Raptor is a single-seat, twin-engine, all-weather stealth tactical fighter aircraft developed for the United States Air Force (USAF). The result of the USAF's Advanced Tactical Fighter program, the aircraft was designed primarily as an air superiority fighter, but has additional capabilities including ground attack, electronic warfare, and signals intelligence roles. Lockheed Martin is the prime contractor and was responsible for the majority of the airframe, weapon systems, and final assembly of the F-22, while program partner Boeing provided the wings, aft fuselage, avionics integration, and training systems. The aircraft was variously designated F-22 and F/A-22 prior to formally entering service in December 2005 as the F-22A. Despite a protracted development as well as operational issues, the USAF considers the F-22 a critical component of its tactical air power, and states that the aircraft is unmatched by any known or projected fighter. The Raptor's combination of stealth, aerodynamic performance, and situational awareness gives the aircraft unprecedented air combat capabilities. The high cost of the aircraft, a lack of clear air-to-air missions due to delays in Russian and Chinese fighter programs, a ban on exports, and development of the more versatile and lower cost F-35 led to the end of F-22 production. A final procurement tally of 187 operational production aircraft was established in 2009 and the last F-22 was delivered to the USAF in 2012. Development Origins In 1981 the U.S. Air Force developed a requirement for an Advanced Tactical Fighter (ATF) as a new air superiority fighter to replace the F-15 Eagle and F-16 Fighting Falcon. Code named "Senior Sky", this program was influenced by the emerging worldwide threats, including development and proliferation of Soviet Su-27 "Flanker"- and MiG-29 "Fulcrum"-class fighter aircraft. It would take advantage of the new technologies in fighter design on the horizon, including composite materials, lightweight alloys, advanced flight control systems, more powerful propulsion systems, and stealth technology. The request for proposals (RFP) was issued in July 1986 and two contractor teams, Lockheed/Boeing/General Dynamics and Northrop/McDonnell Douglas, were selected on 31 October 1986 to undertake a 50-month demonstration phase, culminating in the flight test of two technology demonstrator prototypes, the YF-22 and the YF-23. Each design team produced two prototype air vehicles, one for each of the two engine options. The Lockheed-led team employed thrust vectoring nozzles on YF-22 for enhanced maneuverability in dogfights. The ATF's increasing weight and cost drove out certain requirements during development. Side-looking radars were deleted, and the dedicated infra-red search and track (IRST) system was downgraded from multi-color to single color and then deleted as well. However, space and cooling provisions were retained to allow for future addition of these components. The ejection seat requirement was downgraded from a fresh design to the existing McDonnell Douglas ACES II. After the flight test demonstration and validation of the prototypes, on 23 April 1991, Secretary of the USAF Donald Rice announced the YF-22 as the winner of the ATF competition. The YF-23 design was considered stealthier and faster while the YF-22 was more maneuverable. The aviation press speculated that the YF-22 was also more adaptable to the U.S. Navy's Navalized Advanced Tactical Fighter (NATF), but by 1992, the Navy had abandoned NATF. Production and Procurement Prime contractor Lockheed Martin Aeronautics manufactured the majority of the airframe and performed final assembly at Dobbins Air Reserve Base in Marietta, Georgia; program partner Boeing Defense, Space & Security provided additional airframe components as well as avionics integration and training systems. F-22 production was split up over many subcontractors across 46 states to increase Congressional support, though this production split may have contributed to increased costs and delays. Many capabilities were deferred to post-service upgrades, reducing the initial cost but increasing total program cost. Production supported over 1,000 subcontractors and suppliers and up to 95,000 jobs. The F-22 had several design changes from the YF-22. The swept-back angle of the leading edge was decreased from 48° to 42°, while the vertical stabilizers were shifted rearward and decreased in area by 20%. To improve pilot visibility, the canopy was moved forward 7 inches (18 cm), and the engine intakes moved rearward 14 inches (36 cm). The shapes of the wing and stabilator trailing edges were refined to improve aerodynamics, strength, and stealth characteristics. Increasing weight during development caused slight reductions in range and aerodynamic performance. The first F-22, an engineering and manufacturing development (EMD) aircraft named Raptor 4001, was unveiled at Marietta, Georgia on 9 April 1997, and first flew on 7 September 1997. In 2006, the Raptor's development team, composed of over 1,000 contractors and the USAF, won the Collier Trophy, American aviation's most prestigious award. The F-22 was in production for 15 years, at a rate of roughly two per month during peak production. The USAF originally envisioned ordering 750 ATFs at a cost of $26.2 billion, with production beginning in 1994. The 1990 Major Aircraft Review led by Secretary of Defense Dick Cheney reduced this to 648 aircraft beginning in 1996. By 1997, funding instability had further cut the total to 339, which was again reduced to 277 F-22s by 2003. In 2004, the Department of Defense (DoD) further reduced this to 183 operational aircraft, despite the USAF's preference for 381. In 2006, a multi-year procurement plan was implemented to save $15 billion but raise each aircraft's cost. That year the program's total cost was projected to be $62 billion for 183 F-22s distributed to seven combat squadrons. In 2007, Lockheed Martin received a $7.3 billion contract to increase the order to 183 production F-22s and extend manufacturing through 2011. In April 2006, the Government Accountability Office (GAO) assessed the F-22's cost to be $361 million per aircraft, with $28 billion invested in development and testing; the Unit Procurement Cost was estimated at $178 million in 2006, based on a production run of 181 aircraft. It was estimated by the end of production, $34 billion will have been spent on procurement, resulting in a total program cost of $62 billion, around $339 million per aircraft. The incremental cost for an additional F-22 was estimated at about $138 million in 2009. In March 2012, the GAO increased the estimated cost to $412 million per aircraft. Ban on Exports The F-22 cannot be exported under American federal law to protect the stealth technology and other high-tech features. Customers for U.S. fighters are acquiring earlier designs such as the F-15 Eagle and F-16 Fighting Falcon or the newer F-35 Lightning II Joint Strike Fighter, which contains technology from the F-22 but was designed to be cheaper, more flexible, and available for export. In September 2006, Congress upheld the ban on foreign F-22 sales. Despite the ban, the 2010 defense authorization bill included provisions requiring the DoD to prepare a report on the costs and feasibility for an F-22 export variant, and another report on the impact of F-22 export sales on U.S. aerospace industry. Some Australian politicians and defense commentators proposed that Australia should attempt to purchase F-22s instead of the planned F-35s, citing the F-22's known capabilities and F-35's delays and developmental uncertainties. However, the Royal Australian Air Force (RAAF) determined that the F-22 was unable to perform the F-35's strike and close air support roles. The Japanese government also showed interest in the F-22 for its Replacement-Fighter program. The Japan Air Self-Defense Force (JASDF) would reportedly require fewer fighters for its mission if it obtained the F-22, thus reducing engineering and staffing costs. However, in 2009 it was reported that acquiring the F-22 would require increases to the defense budget beyond the historical 1 percent of GDP. With the end of F-22 production, Japan chose the F-35 in December 2011. Israel also expressed interest, but eventually chose the F-35 because of the F-22's price and unavailability. Design The F-22 Raptor is a fifth-generation fighter that is considered fourth generation in stealth aircraft technology by the USAF. It is the first operational aircraft to combine supercruise, supermaneuverability, stealth, and sensor fusion in a single weapons platform. The Raptor has clipped delta wings with a reverse sweep on the rear, four empennage surfaces, and a retractable tricycle landing gear. Flight control surfaces include leading and trailing-edge flaps, ailerons, rudders on the canted vertical stabilizers, and all-moving horizontal tails; these surfaces also serve as speed brakes. The aircraft's dual Pratt & Whitney F119-PW-100 afterburning turbofan engines are closely spaced and incorporate pitch-axis thrust vectoring nozzles with a range of ±20 degrees; each engine has maximum thrust in the 35,000 lbf (156 kN) class. The F-22's thrust to weight ratio in typical combat configuration is nearly at unity in maximum military power and 1.25 in full afterburner. Maximum speed without external stores is estimated to be Mach 1.82 during supercruise and greater than Mach 2 with afterburners. The F-22 is among only a few aircraft that can supercruise, or sustain supersonic flight without using fuel-inefficient afterburners; targets can be intercepted which subsonic aircraft would lack the speed to pursue and an afterburner-dependent aircraft would lack the fuel to reach. The Raptor's high operating altitude is also a significant tactical advantage over prior fighters. The use of internal weapons bays permits the aircraft to maintain comparatively higher performance over most other combat-configured fighters due to a lack of aerodynamic drag from external stores. The F-22's structure contains extensive amounts of high-strength materials to withstand stress and heat of sustained supersonic flight. Respectively, titanium alloys and composites comprise 39% and 24% of the aircraft's structural weight. The F-22 is highly maneuverable at both supersonic and subsonic speeds. Computerized flight control system and full authority digital engine control (FADEC) make the aircraft highly departure resistant and controllable at aggressive pilot inputs. The Raptor's relaxed stability and powerful thrust vectoring powerplants enable the aircraft to turn tightly and perform very high alpha (angle of attack) maneuvers such as the Herbst maneuver (J-turn) and Pugachev's Cobra. The aircraft is also capable of maintaining over 60° alpha while having some roll control. The Raptor's aerodynamic performance, sensor fusion, and stealth work together for increased effectiveness. Altitude, speed, and advanced active and passive sensors allow the aircraft to spot targets at considerable ranges and increase weapons range; altitude and speed also complement stealth's ability to increase the aircraft's survivability against ground defenses such as surface-to-air missiles. Category:Warplanes